| Nep·tune   (nĕ p t n′ , -ty n′ ) 
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               n.1. a.  Roman Mythology   The god of water, later identified with the Greek Poseidon. b.  The sea. 2.  The eighth planet from the sun, having a sidereal period of revolution around the sun of 164.8 years at a mean distance of 4.5 billion kilometers (2.8 billion miles), a mean equatorial diameter of 49,528 kilometers (30,775 miles), and a mass 17.25 times that of Earth. 
 [Latin Neptūnus.] 
 Nep·tuni·an (-tnē-ən, -ty-) adj.  (click for a larger image)Neptune top:the Roman god bottom: the planet Neptune  (click for a larger image)Neptune |